They are paid wholesale for their labor
Hmmm, I thought they were paid exactly what they agreed to.
Yes, but "agreed to" is not the same thing as "fair price". Granted the definitions of that is up for debate.
Sure... folks "agree" to all kinds of bad deals out of desparation.
But ultimately, the factory owner sets both the price for labor and the price for goods in the market. And for a long time that echelon has had preferred access to many things to ensure that the numbers always work in their favor, in a 100 ways.
Everything from the convention of "no haggling" in a retail store to "people shouldn't talk about their pay"... there's a 100 mind f'ks and well as institutionalized "house edges" (i.e. inflation, unemployment rates centered around 4%, and interest rates monkeyed with to enforce that, and so on) to ensure the status quo remains, no matter the actual numbers.
It's basically the dirty little secret of capitalism... it's based on cheap labor. It's also the dirty little secret of communism.
Same rule everywhere, "House always wins", LOL!
Now it might be different if there was actually somewhere left where you could go and literally be 100% independent, and not die, LOL! But for the most part, every square inch owned and/or controlled by a taxing body.
So in reality, "what they agreed" to... they agreed to without true bargaining parity.
If everyone had true bargaining parity, there would never any such thing as "profit" because a truely fair trade would be at the exact price it took to bring something to market.
So in reality, profit represents the coercive ability of the sell side over the buy side on the output end of things... and the difference between the price of labor and the markup on it represent the coercive capability of factory over individual.
Sure, there are some fields where that's less of an issue. Say medicine or the other "professions". But most of them have barriers to entry, which effectively props up prices.
Bottom line is the same everywhere you look... rarely is it allowed to occur that the working individual gets any leverage.
I'd find it hard to believe that any working adult of any significant years can't see this.